270ah DIY LiFePO4 build

[Kelpie]

Thanks Poey, my thinking was to charge the LA with the solar and mains battery charger in the usual way, and let the B2B charge the LFP? I'll check out those videos...

I am going down essentially this route, with two differences.
Firstly, I am building the battery myself using prismatic cells and a basic BMS (total cost £407, for 4x272Ah cells and a 120A BMS).
Secondly I am adding more solar panels and these will charge the new battery. This is much more efficient than using them to charge the lead-acid and then charging the lithium using the B2B.

Small update- good news, the BMS arrived. I chose the JBD, which is the hardware used by Overkill Solar who are well regarded as a basic value-for-money option. I did look at getting an Overkill but they said they wouldn't have the model I needed in stock for at least a month. Bad news, my PSU is playing up again, I caught it creeping up to 20v (I don't think the cells were seeing that- but I knew something was wrong because the current had increased). So I've stopped charging for now, and will resume once I have the BMS connected. I'm not sure what to do about top balancing now, since I no longer trust the PSU...

 

[Poey50]

I am going down essentially this route, with two differences.
Firstly, I am building the battery myself using prismatic cells and a basic BMS (total cost £407, for 4x272Ah cells and a 120A BMS).
Secondly I am adding more solar panels and these will charge the new battery. This is much more efficient than using them to charge the lead-acid and then charging the lithium using the B2B.

Small update- good news, the BMS arrived. I chose the JBD, which is the hardware used by Overkill Solar who are well regarded as a basic value-for-money option. I did look at getting an Overkill but they said they wouldn't have the model I needed in stock for at least a month. Bad news, my PSU is playing up again, I caught it creeping up to 20v (I don't think the cells were seeing that- but I knew something was wrong because the current had increased). So I've stopped charging for now, and will resume once I have the BMS connected. I'm not sure what to do about top balancing now, since I no longer trust the PSU...

Can you return your faulty PSU and get a new one? This is the one I bought - it was very well reviewed independently and has been faultless. https://www.amazon.co.uk/（precision...20244818&sprefix=10+amp+power,aps,154&sr=8-50

An alternative is a 5 amp 3.65 volt charger from GWL. I have this onboard in case I ever want to charge one cell. Charger 3.6V/5A for LiFePO4 cells (1 cell) | shop.GWL.eu

 

[Kelpie]

Can you return your faulty PSU and get a new one? This is the one I bought - it was very well reviewed independently and has been faultless. https://www.amazon.co.uk/（precision-00-01V，00-01A）4-Digital-Adjustable-Switching-Spectrophotometer/dp/B07MDVTTM7/ref=sr_1_50?crid=1DKJZG6R9N3EU&dchild=1&keywords=10+amp+power+supply&qid=1620244818&sprefix=10+amp+power,aps,154&sr=8-50

An alternative is a 5 amp 3.65 volt charger from GWL. I have this onboard in case I ever want to charge one cell. Charger 3.6V/5A for LiFePO4 cells (1 cell) | shop.GWL.eu

I bought the same Longwei PSU, but from eBay as I try to avoid Amazon if possible. The first one I got several months ago and found it stopped putting out any voltage, so the seller sent out a replacement. The new one then sat unused for ages until last week. I might be too late to return it, but I suppose that depends on the warranty.

 

[sailaboutvic]

That's a bugger , I wouldn't try and balance cell if it strays , cells are going to take quite a while and you not going to be able to sit there looking at them all the time.
Mine Power supple is also a Longwei and I had no problems with it ,
Before buying mine I was under the impression once I finish using it , it be redundant but it's been useful in charging all sort of stuff even my old laptop and now if I need 12v to test anything rather then plugging onto the batteries ,I just use the power supply ?
Hopefully you can return it .

 

[sailaboutvic]

I am going down essentially this route, with two differences.
Firstly, I am building the battery myself using prismatic cells and a basic BMS (total cost £407, for 4x272Ah cells and a 120A BMS).
Secondly I am adding more solar panels and these will charge the new battery. This is much more efficient than using them to charge the lead-acid and then charging the lithium using the B2B.

I'm finding nearly all my charging is bein done by my panel 750w ,
only if we had a few days of clouds and we happen to be moving under engine will I let the B2B help to charge ,
Not sure what it be like back in the UK but here in the Med I'm having to find ways of using power most days other wise they reach their peak and sit for the rest of they time on 13.5v ( float setting) ,
I'm starting to think it maybe to some advantage to drop that setting to 13.4/13..3v once we stop using the induction hob in the evening .
I'm still trying to understand why the people who seen to know what they talking about on other forums still talk about charging to 14.4v .

 

[Poey50]

I'm finding nearly all my charging is bein done by my panel 750w ,
only if we had a few days of clouds and we happen to be moving under engine will I let the B2B help to charge ,
Not sure what it be like back in the UK but here in the Med I'm having to find ways of using power most days other wise they reach their peak and sit for the rest of they time on 13.5v ( float setting) ,
I'm starting to think it maybe to some advantage to drop that setting to 13.4/13..3v once we stop using the induction hob in the evening .
I'm still trying to understand why the people who seen to know what they talking about on other forums still talk about charging to 14.4v .

I see Rod Collins now uses 13.8 volts, Vic. His 400ah pack is 12 years old and still showing full capacity. We've just begun to use our boat in the UK with regular use of fridge and heater (it's blooming freezing here) but we can't use our available power so I'm regularly switching off solar and the alternator.

 

[sailaboutvic]

I see Rod Collins now uses 13.8 volts, Vic. His 400ah pack is 12 years old and still showing full capacity. We've just begun to use our boat in the UK with regular use of fridge and heater (it's blooming freezing here) but we can't use our available power so I'm regularly switching off solar and the alternator.

Rod may say his pack is 12 years old and I don't disbelieve him , but how many has he used it ? How Much has he drawer from it over 12 years . ?
It be interested to see if my pack still going in 12 years if I'm still cruising then at the rate we use it.
Only time will tell .
Good to see he now saying to charge at 13.8v , I wonder why after 12 years at 14.4v he now drop to 13.8v
Especially as he saying he pack as not lose any capicity in 12 years .

 

[Kelpie]

Mu understanding is that 14.4v is useful for balancing- but presumably you only need to do this every few months, if that? And you could always do a parallel top balance instead?

I'm really puzzled by the Longwei. That's two bad ones I seem to have had. Perhaps the seller got a bad batch or something.

 

[sailaboutvic]

Mu understanding is that 14.4v is useful for balancing- but presumably you only need to do this every few months, if that? And you could always do a parallel top balance instead?

I'm really puzqzled by the Longwei. That's two bad ones I seem to have had. Perhaps the seller got a bad batch or something.

I done expect to balance mine again unless I see cells drifting apart .
I will every few month charge them to 14.2v as a one off .
My PS once set stays set . I think you been unlucky
Shame really as I'm sure you want to get on with now .

 

[vas]

slightly off-topic, was reading this morning that Li batteries production costs are dropping and car manufacturers having reached the target of 1kWh @ 100USD are now aiming to drop the price to 60USD and are expecting to reach that within the next 12m!
Doing a quick calc it seems that using LiFEPO4 we are batteries only sans BMS at the 100-110USD/kWh going to the cheapest alibaba sales (and hoping customs don't charge us) Am I right?

V.

 

[Poey50]

Rod may say his pack is 12 years old and I don't disbelieve him , but how many has he used it ? How Much has he drawer from it over 12 years . ?
It be interested to see if my pack still going in 12 years if I'm still cruising then at the rate we use it.
Only time will tell .
Good to see he now saying to charge at 13.8v , I wonder why after 12 years at 14.4v he now drop to 13.8v
Especially as he saying he pack as not lose any capicity in 12 years .

He has used over 2000 cycles, most to 80% depth of discharge. I'm not sure how long he has been at 13.8v ...I don't think it was that recent. He has lost a small amount of capacity but is still over 400ah as reported earlier this week.

 

[Poey50]

Mu understanding is that 14.4v is useful for balancing- but presumably you only need to do this every few months, if that? And you could always do a parallel top balance instead?

I'm really puzzled by the Longwei. That's two bad ones I seem to have had. Perhaps the seller got a bad batch or something.

I'm suspecting your supplier.

 

[sailaboutvic]

He has used over 2000 cycles, most to 80% depth of discharge. I'm not sure how long he has been at 13.8v ...I don't think it was that recent. He has lost a small amount of capacity but is still over 400ah as reported earlier this week.

We done 16 cycles so far since we fitted them

 

[Poey50]

I don't often post on particular cells but these are picking up a bit of interest because they can ship with fixed studs. Total shipped price to UK for a 4S nominal 12 volt 280ah pack = USD 446 - around £320. Half what I paid a year ago.

Lifepo4 Deep Cycle Battery Cell 280ah 3.2v Lifepo4 Battery For Home Energy System - Buy Lifepo4 Battery 280ah,Lifepo4 Battery 3.2v,Lifepo4 Battery Product on Alibaba.com

 

[Poey50]

slightly off-topic, was reading this morning that Li batteries production costs are dropping and car manufacturers having reached the target of 1kWh @ 100USD are now aiming to drop the price to 60USD and are expecting to reach that within the next 12m!
Doing a quick calc it seems that using LiFEPO4 we are batteries only sans BMS at the 100-110USD/kWh going to the cheapest alibaba sales (and hoping customs don't charge us) Am I right?

V.

If you see what I posted above, that delivered cost is pretty much at 1kWh per £100 delivered price. That should include any import duty. That feels quite a significant moment. How much further it will drop .. who can tell?

 

[TernVI]

If you see what I posted above, that delivered cost is pretty much at 1kWh per £100 delivered price. That should included any import duty. That feels quite a significant moment. How much further it will drop .. who can tell?

One opinion is that there is a 'price floor' where storage of 'excess' wind and solar energy for sale back to the grid becomes a reality, and the grid operators will buy everything the battery makers can produce.
Some have said that might be around $50 per kWh.

 

[Kelpie]

If I was in the lead-acid business right now I would be very worried...

 

[vas]

If you see what I posted above, that delivered cost is pretty much at 1kWh per £100 delivered price. That should include any import duty. That feels quite a significant moment. How much further it will drop .. who can tell?

checked for 8S (24V) works out 108euro/kWh, not bad, not to mention that if I've survived the last 4yrs with 225/2 Ah, why should I go for 0.8*280Ah. 110Ah usable (trojans) vs 224 (lifepo4)
makes you think if one should get a 200Ah package (not that I can find many - fe this seller only does 280 and 100)

BTW, probably asked before but don't remember:

in LifePO4 land, is it better to have the bank going daily from 95-70% and same all over again (charging with solar) or a smaller pack that would go daily 95-50%?
approx diff of using a 280Ah vs a 200Ah pack. Not liveaboard so this applies for 60-90days pa.

V.

 

[sailaboutvic]

If you don't need that power 90% to what ever you use I personlly would think would be ok

 

[adwuk]

I understand that the move from lead acid to LifePO4 requires a shift in mentality about the state of charge when a boat is not in use, and then I twigged that a recent addition DJI made to their drones might be worth considering. In short, when a drone battery is neither in use nor charging, the battery firmware enables some kind of load to gently run down the battery to about 50% at which point it stops. Would that be possible so that idiots like me don't have to think about it?